Apresentação Pública da Proposta de Tese de Doutoramento em Física Atómica e Molecular da Universidade Nova de Lisboa do Mestre César António Cantanhede Godinho

Apresentação Pública da Proposta de Tese de Doutoramento em Física Atómica e Molecular  da Universidade Nova de Lisboa

Aluno:   César António Cantanhede Godinho

Tema: High-precision reference-free measurements of x-ray transition energies in Highly-Charged Ions using a custom made vacuum Double flat-Crystal

 Presidente:

Doutora Maria de Fátima Guerreiro da Silva Campos Raposo, Professora Catedrática, Faculdade de Ciências e Tecnologia da
Universidade NOVA de Lisboa.

Comissão de acompanhamento de tese:

Doutor Daniel Galaviz Redondo, Professor Auxiliar da Faculdade de Ciências da Universidade de Lisboa (Membro externo da CAT).

Doutor Jorge Felizardo Dias Cunha Machado,  Professor Auxiliar, Faculdade de Ciências e Tecnologia da Universidade NOVA de Lisboa (Orientador e membro da CAT).

Dia: 04/05/2026

Hora: 15h00 às 16h00
Local:  Sala 3 Cantina

Sumário do Tema de Doutoramento:

This thesis will focus simultaneously on two distinct works that fall within the Highly Charged Ions field as common ground. Firstly I will focus on the setup, assembly and control of a double crystal spectrometer (DCS) for high-precision soft X-ray measurements being developed at Laboratoire Kastler-Brossel in Paris alongside with its twin experiment at the NOVA university. The goal of this is to modernize the preexisting system at Paris and build a new one in Lisbon. This modernization is essential to the operation of both devices which are highly appreciated by the physics community regarding its high resolution, reference-free (in this case) measurements. These in-depth measurements can help us understand and test bound state quantum electrodynamic effects (BSQED), provide solid foundation as calibration on other experiments, and ultimately slowly rebuild a high precision database which, as of today, contains many old and outdated values. The main goal is to measure multiple soft X-ray transitions with meV precision [1], and build a system that reliably allows one to do this without much hassle, allowing to focus on the data analysis and compiling, automating as much of the experimental process as possible. Secondly, I will focus on the analysis of muonic boron X-ray measurements made by the QUARTET collaboration were we aim to precisely measure the charge radii of many light nuclei as well as their isotope energy shift with an improvement in accuracy of up to 20 times [2] the current value. These measurements are a window to better understand nuclear physics at low energies and for both experimental and theoretical applications in simple atomic systems providing advancement of the BSQED theory, proven useful for the search of physics beyond the Standard Model. In this work, the goal is to precisely determine the isotope-shift from 10B and 11B in muonic K-range transitions. The experiment employs a Metallic Magnetic Calorimeter (MMC) detector, custom built by the Heidelberg university specialist group. One of the main challenges of the data analysis is the detector dependence on temperature variations as well as its sensitivity to many other external effects (e.g. mobile RF frequency band, room temperature, ...). And finally, the analysis of both previous points relies on a Bayesian fitting algorithm (nested sampling), provided by the Nested_Fit [3] package. This is also, secondarily, a topic where this thesis is heavily contributing, considering I am now one of the package maintainers. Reference to the Nested_Fit software will be brief on this report, but will cover the main aspects where this work impacts its ecosystem.